At first it seemed as if Nat Geo — the National Geographic Channel — would avoid the trend of cable TV in that it would provide higher-minded programming, an antidote to the scripted garbage of “reality shows” that now dominate cable entertainment networks.

And, at first, Nat Geo didn’t disappoint. Documentaries and regular programs such as “Locked Up Abroad” — about folks imprisoned in filthy prisons and in basements by terrorist groups in the Middle East, Asia and in Central and South America — made for strong, thoughtful TV.

But then slowly, and now with a rush, Nat Geo has flipped. Its focus increasingly has been low and voyeuristic, urging us to examine and enjoy fringe lunatics, some who seem too rehearsed to be real.

So now shows such as “Taboo,” which features a dominatrix wearing a leather bra and wielding a whip, and “Doomsday Preppers,” in which folks are driven to action by the anticipation of Armageddon, have invaded the Nat Geo Channel, named after the 125-year-old magazine that has taken us all over the world while taking the high road.

A recent stop at Nat Geo immediately included a woman, perhaps 20, smiling and speaking toward a TV camera. “After a good make-out session,” she said, “I’m ready to pull down my pants for you.”

The show was Nat Geo’s “Sex: How It Works,” and the time of its broadcast was 4 p.m.

Such a study might be very valuable to the alcohol industry, as it likely tells those in the lower half and those who finished out the Top 10 that they have to do better — much better.

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As fee disputes with Time Warner Cable — hassles that threaten the removal of popular channels and networks — now seem to arrive monthly, it’s worth keeping in mind that if TWC chooses to be truthful with the public in presenting its side it’ll be in defiance of a 35-year-old tradition among cable giants.

Consider that last September, after finally agreeing to carry the 9-year-old NFL Network, TWC quickly began to sell it to subscribers as something they can’t possibly live without.

Prior to that, TWC explained that it hadn’t made a deal with the NFL Network because no one wanted it.

Not that the NFL Network wasn’t built on an ugly cable money-grab, too. The NFL simply grabbed a bunch of games that normally would have been played Sunday afternoons on CBS and Fox, and threw them on Thursday nights. Presto! The NFL Network! Please remit.

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The latest wave in promotional public relations is to shamelessly exploit any and every tragedy for publicity, a little salesmanship and even ego gratification.

Thus, the Newtown, Conn., grammar school massacre was soon followed by e-mails pitching the news media access to “experts” in the field of grief counseling, child psychiatry and whatever other connections could be made to the slaughter of children in exchange for publicity.

Here’s one that arrived July 15:

“With the tragic news of the death of ‘Glee’ star Cory Monteith over the weekend, please let me know if you are working on any pieces about the topic and would like to speak to an expert . . . Please let me know if you are interested and I would be happy to set something up.”

This ghoulish pitch was sent by the Fifth Avenue firm “DKC Public Relations, Marketing and Government Affairs.”